MEASUREMENT OF THE DIFFUSIVITY OF OXYGEN IN HIGH-TEMPERATURE LIQUID SILVER BY ELECTROCHEMICAL METHOD

Abstract

Recently liquid silver was usually used as the electrode for the research on the metallurgy with controlled oxygen flow by means of a galvanic cell employing solid oxygen-ion conducting electrolyte.The diffusivity of oxygen in liquid silver has a practical significance and theoretical value on understanding the kinetics process of electrochemical reaction with controlled oxygen flow.However,the predecessors' data for the oxygen diffusivities were generally below 1473 K and could not satisfy the requirements for the research on the metallurgy with controlled oxygen flow at higher temperatures.In the present study the diffusivities of oxygen in liquid silver in the temperature range of 1473 to 1773 K were determined by potentiostatic method,in which the cylindrical-like zirconia base solid electrolyte cell arrangement,(+)Pt|air|ZrO_2(MgO)|[O]_(Ag(l))|Ir(-),was employed.The diffusivity of oxygen(D_o) in liquid silver contained in a zirconia tube was calculated from the change of the external current with time by applying a preselected voltage on the electrochemical cell.On the assumption of Arrhenius equation,least square treatment of the results gave the following relation, D_O =(1.11±0.04)×10~(-3)exp(-25573±1718/RT),of which the confidence limit reached 95%.The present experimental results are in close agreement with those extrapolated from the data of other investigators at low temperature.The diffusivity of oxygen in liquid silver at 1773 K is(1.96±0.28)×10~(-4) cm~2/s.